Let us acknowledge the obvious. If an elite runner thought it would make him faster, he would compete wearing a beanie outfitted with a propeller. On his derriere.

More conventionally, if a shoe company were to design footwear which would guarantee its wearer would be 4% quicker….well, what part of evident don’t you understand?

But being guilty of seeking every tiny performance edge is not the tricky part. Rather, in this age of rapid scientific advances, there is the concern regarding potentially artificial assistance.

Ethicists and sports officials have been worried about this kind of thing for a while. And now wearers of the space-age Vaporfly running shoe, fashioned by the sportswear giant Nike, have produced history’s five fastest men’s marathon times and four of the 10 fastest women’s marathons in the last two years.

Is such equipment merely maximizing human capacity? Just helping fulfill the logically aspirational Olympic motto—citius, altius, fortius (“faster, higher, stronger” in Latin)? Or is it crossing the fuzzy line into technology doping, adding a furtivus (loosely translated, “sneakier,”) to the motto?

With the Vaporfly, an extra-thick mid-sole with a carbon fiber plate acts like a spring, compressing when the runner lands, storing energy from the foot strike and expanding again to return that stored energy into the ground to push the runner forward. Independent studies have confirmed a 4% efficiency boost.

Is this situation anything like when swimming officials were wrestling with the acceptability of full bodysuits 20 years ago, after those suits were found to provide buoyancy and muscle constriction that worked to reduce fatigue? (Eventually those suits were banned in international competition.)

Is it similar to the NBA’s prohibition in 2009 of Athletic Propulsion Labs sneakers, which featured a ballyhooed “Load ‘N Launch” technology to increase vertical leap and thus were judged to be supplying an undue advantage?

In the slapstick 1961 movie “The Absent-minded Professor,” the application of “flubber” (flying rubber) to the shoes of the school’s basketball players—allowing them to soar above the opposition like kangaroos against elephants—clearly was as unjust as it was comical.

But science in fact lurks as a possible threat to an even playing field. Golf (club technology), baseball (bat materials) and football (Stickum) all have implemented restrictions on paraphernalia. Thirteen years ago, track and field’s governing body barred such aids as springs and wheels in athletic shoes, though its basic rule is vague: Shoes may not confer “any unfair assistance or advantage” and must be “reasonably available” to all competitors.

Vaporfly is available for $250 a pair, though a runner under contract with Nike surely can get a break there. For now, the shoe remains an acceptable accoutrement, though track’s international federation has formed a working group of athletes, scientists and legal experts to review the Vaporfly and is expected to announce a “temporary suspension of any fresh shoe technology” until after this summer’s Tokyo Olympics.

Epilogue: In 1960, Ethiopia’s Abebe Bikila ran the 26-mile, 385-yard Olympic marathon barefoot. And won. In 1964, he won the Olympic marathon again. Wearing shoes. Technology? Or just time marching on?